Hardware Reference
In-Depth Information
Figure 2-12.
Raspberry Pi showing the eth0 IP
How do we perform this magical feat? Well, the trick is in another Adafruit project kit:
the
LCD Pi Plate
. The lovely and talented folks over at Adafruit have designed a simple
way to stack an 16 x 2 LCD and a simple keypad right on top of a Raspberry Pi. It comes
as an unassembled kit, but putting it together is simple.
Build the LCD Pi Plate
To assemble the LCD Pi Plate, you will need:
• A soldering iron (and solder)
• A LCD Pi Plate Kit (it includes a 16x2 Blue LCD, but Adafruit sells other colors)
• Fine wire cutters
• A narrow-tipped Phillips screwdriver
• Tall
stacking header
(optional)
There are many different ways to connect an LCD to a Raspberry Pi, but the LCD Pi
Plate has some notable advantages for this hack. The LCDs that Adafruit uses require
a lot of digital pinouts (six to nine, depending on the functionality of the LCD device).
If you attached this device directly to your Raspberry Pi, you'd take up a lot of GPIO
pins simply to add an LCD.
But the LCD Pi Plate provides a stackable way to add an LCD (think Arduino shield)
that uses only two pins, the I2C pins. Also, because of how the I2C bus works, you can
attach additional devices to those pins and they will appear on the I2C bus (as long
as they do not have conflicting addresses). On top of that, you get five push buttons
that you can use to interact with the LCD.
Adafruit has a
fantastic tutorial
that walks you through the process of assembling the
LCD Pi plate. But if you're unable to view it for some reason, the kit is very straight-
forward.
Basically, you solder in the two 220 ohm resistors (labeled Red, Red, Brown, Gold) in
the slots labeled RED and BLUE, and the 1 remaining resistor (330 ohm, labeled Or-
ange, Orange, Brown, Gold) goes in the slot labeled GREEN. Trim the excess leads
